Over the last few years, understanding of genetic engineering methods has progressed to a new level. The latest method involves clustered regularly interspaced short palindromic repeats (CRISPR). These segments of DNA are characterized by short bacterial virus or plasmid sequences that are interspersed between a series of spacers made up of repeated bases.

The function of these DNA segments plays an integral part in a cell’s immune response to foreign genetic material. The stretches of DNA serve as a memory bank for a cell to recognize exogenous material, cut viral or bacterial DNA into short pieces and ultimately stop the proliferation of infection. A few pieces of viral or bacterial DNA are captured and saved, and then inserted between the spacers. Collectively, the repeated bases and viral or bacterial sequences make up the CRISPR-associated (Cas) genes that encode for nucleases or immune-defense proteins.

Genetic engineers are able to harness this mechanism to alter genomes of entire cell populations. In particular, the Cas9 system is used to edit genes by adding, deleting or exchanging parts of sequences at precise locations. The process has been applied to the creation of knockout mice, in which specific disease traits can be expressed to test potential therapeutics.

CRISPR/Cas systems are replacing older methods, such as transcription activator-like effector nuclease (TALEN) and zinc-finger nuclease (ZFN), due to their relative ease of use and flexibility. The main advantage of the CRISPR system is its use of a short guide RNA (gRNA) sequence that can be developed easily and adjusted based on the success or failure of an assay. TALEN and ZFN require engineering of enzymes to recognize a specific DNA sequence.

End-users can obtain CRISPR plasmids from a variety of sources. Addgene, a nonprofit repository, has a collection of more than 40,000 plasmids through its community of over 2,200 labs. End-users can submit their own plasmids for storage or purchase plasmids that colleagues have contributed.

Integrated DNA Technologies manufactures the gBlock Gene Fragments, covering over 14,000 gene fragments that can be used to create Cas9 enzymes. The fragments are available in lengths of 125–2000 bp and are priced from $90 to $330. Thermo Fisher Scientific offers GeneArt CRISPR products, including the CRISPR-Cas9 all-in-one expression vector, Cas9 mRNA and Cas9 protein. It also offers library services and custom-designed cell line–engineering services.

CRISPR gene editing has been a boon to genetic engineering, with a growing list of applications, such as stem cell research, gene therapy, disease-resistant transgenic plants and the creation of animal disease models. It is also a driving force for the $35 billion life science instrument market, particularly for instruments such as DNA sequencing, PCR, transfection (including electroporation) and automated DNA extraction systems.

CRISPR at a Glance:

Leading Suppliers

• Addgene

• Integrated DNA

Technologies

• Thermo Fisher Scientific

Largest Markets

• Academia

• Government

• Biotechnology

Cost

• $45–$400